significant improvements and streamlining to the RQT GUI interface

[Antonio-Griego]

First, a disclaimer and apology: the single massive commit is the
result of having to cherry pick the many apsects of this feature
from other branches that were merged or partially merged into the
now-deleted development branch.

That being said, there is a lot of really cool things in this feature:

• Unique Rover Colors: You can check this box on the sensor display
  tab to have reach rover's trail on the Map Frame be uniquely
  colored. There are 8 unique colors, if you are using more than
  8 rovers than the colors are assigned in a cycle. For example,
  rover 0 and rover 8 will be the same color, etc.

• Global Frame: You can check this box on the sensor display tab to
  reposition the Map Frame trails of all rovers to be as they appear
  in the Gazebo world. That is, the Map Frame displays all rovers
  at (0,0) by default from their Odometry frame of reference. This
  check box corrects that by offsetting their trails by their
  Gazebo spawn points. Unfortunately, this is for simulated rovers
  only at this time.

• Savable Gazebo World: You can check this box on the simulation control
  tab to build a simulation's Gazebo world without rovers, walls,
  ground texture, or a collection zone will be created. The purpose of
  this option is to generate tag distributions using the Uniform,
  Clustered, or Power Law in a way that you can save the world file from
  Gazebo and re-use that same distribution later using the Custom world
  option. It will also load much faster as well when loading a pre-built
  distribution.

• Unbounded Round Type: In addition to Preliminary and Final, you can now
  select the "unbounded" round type which has no barrier walls. When
  selected, you can also choose the square arena size from the accompanying
  drop down menu. When creating target distributions using Uniform,
  Clustered, or Power Law, the apriltag cubes will be spread out to fill
  the size of the arena you chose.

• Number of Cubes: When building worlds with the Uniform or Clustered
  distributions, you can set the total number of cubes generated in
  the simulation control tab. The sizes of clusters are scaled based
  on the total amount of cubes selected. This is useful for building
  worlds with smaller number of cubes for testing without having to
  wait for a long time for the placement of many cubes.

• Simulation Length Timer: There is now an option for a 20 minute timer
  in the Simulation Length timer drop down box.

• Start Visualization On Build: There is now a checkbox that toggles whether
  or not Gazebo is launched immediately when you click the Build Simulation
  button. When unchecked, you must click Toggle Visualization to launch
  Gazebo for your currently running simulation.

• The Task Status tab has been removed: The information previously kept
  in this tab has been moved to the left hand side of the GUI screen
  and is accessible while in both of the other tabs.

• Overall streamlining and beautification(*) of the GUI: There was a lot of
  unused and awkward white space that was condensed and re-allocated so
  that the maximum amount of useful information was available in each
  tab of the RQT GUI.

(*) Based on the writer's biased opinion, grid based layouts are pretty.

[jprod123]

Nice! Saving the gazebo worlds aswell as setting the number of cubes to spawn sounds like a tremendous time saver!

Is it also possible to set the size of the arena from the GUI aswell. This will allow us to scale both the cubes and arena size to get the same block density as if it were a full sized arena under uniform distribution.

[kristiana-rendon]

Working Portion of GUI:

1.) Lots of great new features!
2.) Clearer design
3.) Does not interfere with any rover functionality

Non-Working Portion of GUI:

None

Additional Comment(s):

1.) Could use color legend in map settings
2.) Obstacle avoidance count is saved even after restarting connection

[gmfricke]

GUI looks much better. @kristiana-rendon has tested in hardware.